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Recycling of valuable metals from secondary resources such as waste Li-ion batteries (LIBs) has recently attracted significant attention due to the depletion of high-grade natural resources and increasing interest in the circular economy of metals. In this article, the sulfuric acid leaching of industrially produced waste LIBs scraps with 23.6% cobalt (Co), 3.6% lithium (Li) and 6.2% copper (Cu) was investigated. The industrially produced LIBs scraps were shown to provide higher Li and Co leaching extractions compared to dissolution of corresponding amount of pure LiCoO. In addition, with the addition of ascorbic acid as reducing agent, copper extraction showed decrease, opposite to Co and Li. Based on this, we propose a new method for the selective leaching of battery metals Co and Li from the industrially crushed LIBs waste at high solid/liquid ratio (S/L) that leaves impurities like Cu in the solid residue. Using ascorbic acid (CHO) as reductant, the optimum conditions for LIBs leaching were found to be T = 80 °C, t = 90 min, [HSO] = 2 M, [CHO] = 0.11 M and S/L = 200 g/L. This resulted in leaching efficiencies of 95.7% for Li and 93.8% for Co, whereas in contrast, Cu extraction was only 0.7%. Consequently, the proposed leaching method produces a pregnant leach solution (PLS) with high Li (7.0 g/L) and Co (44.4 g/L) concentration as well as a leach residue rich in Cu (up to 12 wt%) that is suitable as a feed fraction for primary or secondary copper production.

Abstract:The recycling of valuable metals from spent lithium-ion batteries (LIBs) is becoming increasingly important due to the depletion of natural resources and potential pollution from the spent batteries. In this work, different types of acids (2 M citric (C 6 H 8 O 7 ), 1 M oxalic (C 2 H 2 O 4 ), 2 M sulfuric (H 2 SO 4 ), 4 M hydrochloric (HCl), and 1 M nitric (HNO 3 ) acid)) and reducing agents (hydrogen peroxide (H 2 O 2 ), glucose (C 6 H 12 O 6 ) and ascorbic acid (C 6 H 8 O 6 )) were selected for investigating the recovery of valuable metals from waste LIBs. The crushed and sieved material contained on average 23% (w/w) cobalt, 3% (w/w) lithium, and 1-5% (w/w) nickel, copper, manganese, aluminum, and iron. Results indicated that mineral acids (4 M HCl and 2 M H 2 SO 4 with 1% (v/v) H 2 O 2 ) produced generally higher yields compared with organic acids, with a nearly complete dissolution of lithium, cobalt, and nickel at 25 • C with a slurry density of 5% (w/v). Further leaching experiments carried out with H 2 SO 4 media and different reducing agents with a slurry density of 10% (w/v) show that nearly all of the cobalt and lithium can be leached out in sulfuric acid (2 M) when using C 6 H 8 O 6 as a reducing agent (10% g/g scraps ) at 80 • C.

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Sulfation roasting followed by water leaching has been proposed as an alternative route for recycling valuable metals from spent lithium-ion batteries (LIBs). In the present work, the reaction mechanism of the sulfation roasting of synthetic LiCoO 2 was investigated by both thermodynamic calculations and roasting experiments under flowing 10% SO 2 -1% O 2 -89% Ar gas atmosphere at 700°C. The products and microstructural evolution processes were characterized by x-ray diffraction, scanning electron microscope and energy dispersive x-ray spectrometer, and atomic absorption spectroscopy. It was confirmed that Co 3 O 4 was formed as an intermedia product, and the final roasted products were composed by Li 2 SO 4 , Li 2 Co(SO 4 ) 2 , and CoO. The leaching results indicated that 99.5% Li and 17.4% Co could be recovered into water after 120 min of roasting. The present results will provide the basis and solid guidelines for recycling of Li and Co from spent LIBs.

This research presents a sustainable approach for the simultaneous recycling of spent lithium-ion batteries (LIBs) and nickel−metal hydride batteries (NiMHs). First, dissolution of LIBs and NiMHs were found to be mutually copromoted, resulting in above 98% extraction of Li, Co, Ni, and rare-earth elements (REEs) without the need for any oxidant or reductant additions. After leaching, >97% of REEs were recovered as a REEs-alkali double sulfate precipitate with the addition of NaOH and Na 2 SO 4 precipitants. This REEs-free solution was then further processed to separate and recover the battery metals present: Mn, Co, Ni, and Li. The resultant residual solution (rich in NaOH and Na 2 SO 4 ) was redirected to the REEs precipitation step, decreasing both the need of precipitants (e.g., Na 2 SO 4 ) as well as the costs related to the treatment of the high-Na waste solution. Moreover, the Li remaining in the waste solution can be circulated back into the main process, resulting in an exceptionally high Li recovery of >93% in the form of high-purity Li 3 PO 4 (99.95%). This is a marked improvement over the previously reported Li recovery levels of 60−80%. Overall, this newly developed process has considerable environmental and economic advantages for the recovery of valuable metals from mixed LIBs and NiMHs wastes.

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To achieve the global goals related to renewable energy and responsible production, technologies that ensure the circular economy of metals and chemicals in recycling processes are a necessity. The recycling of spent Nd−Fe−B magnets typically results in rare-earth element (REE)-free wastewater that has a high ferric ion concentration as well as oxalate groups and for which there are only a few economically viable methods for disposal or reuse. The current research provides a new approach for the effective recovery of oxalic acid, and the results suggest that during the initial oxalate group separation stage, >99% of oxalate ions can be precipitated as ferrous oxalate (FeC 2 O 4 •2H 2 O) by an ultrasound-assisted iron powder replacement method (Fe/Fe(III) = 2, t u/s = 5 min, T = 50 °C). Subsequently, almost all FeC 2 O 4 •2H 2 O was dissolved using 6 mol/L HCl (T = 65 °C, t = 5 min) and the dissolved oxalates were found to mainly exist in the form of H 2 C 2 O 4 . Furthermore, over 80% of the oxalic acid was recovered via crystallization by cooling the oxalate containing HCl solution to 5 °C. After oxalic acid crystallization, the residual raffinate acid solution can then be recirculated back to the ferrous oxalate leaching stage, to decrease any oxalic acid losses. This treatment protocol for high-iron REE-free solution not only avoids the potential harm to the environment due to the wastewater but also significantly improves the circular economy of chemicals in the typical utilization in permanent magnet recycling processes.